Titanium Nitride Electron-Conductive Contact for Silicon Solar Cells By Radio Frequency Sputtering from a TiN Target
Jing Yu, Pheng Phang, Christian Samundsett, Rabin Basnet, Guru P. Neupan, Xi Yang, Daniel Macdonald, Yimao Wan, Di Yan, Jichun Ye
Abstract
Efficient and stable electron selective materials compatible with commercial production are essential to the fabrication of dopant-free silicon solar cells. In this work, we report an air-stable TiN (titanium nitride) polycrystalline film, deposited using radio frequency sputtering process, as an electron selective contact in silicon solar cells. TiN films deposited at 300 W and 1.5 mTorr exhibit a low contact resistivity of 2.0 mΩ·cm2. Furthermore, the main factors and mechanisms affecting the carrier selectivity properties are also explored. TiN layers as full area rear electron contacts in n-type silicon solar cells have been successfully implemented, even though TiN film contains some oxygen. This process yields a 17% increment in relative efficiency in comparison with reference devices (n-Si/Al contact). Hence, considering the low thermal budget, scalable technique, and low contact resistivity, the TiN layers can pave the way to fabricate high-efficiency selective contact silicon solar cells with a higher degree of reproducibility.